Protein influencing factors enzymatic

Enzymatic reactions are influenced by a variety of solution conditions that must be well controlled in HTS assays. Buffer components, pH, ionic strength, solvent polarity, viscosity, and temperature can all influence the initial velocity and the interactions of enzymes with substrate and inhibitor molecules. Space does not permit a comprehensive discussion of these factors, but a more detailed presentation can be found in the text by Copeland (2000). Here we simply make the recommendation that all of these solution conditions be optimized in the course of assay development. It is worth noting that there can be differences in optimal conditions for enzyme stability and enzyme activity. For example, the initial velocity may be greatest at 37°C and pH 5.0, but one may find that the enzyme denatures during the course of the assay time under these conditions. In situations like this one must experimentally determine the best compromise between reaction rate and protein stability. Again, a more detailed discussion of this issue, and methods for diagnosing enzyme denaturation during reaction can be found in Copeland (2000). 

Zitiianova and others (2006) examined the inhibitory effect of extracts from different kinds of fruits and vegetables on the oxidative damage to proteins in vitro. Dragsted and others (2004) investigated the relative influence of nutritive and nonnutritive factors in fruit and vegetables on oxidative damage and enzymatic defense. Jacob and others... 

In many cases, the role of many post-translational modifications is not well understood, but in some cases they have been found to be required for the biological activity of the protein molecules. In some cases where the enzymatic or co-factor activity of a protein is unaffected by the lack of a specific post-translational modification, it has been found to impact properties such as stability and circulating half-life. Thus, while the lack of glycosylation of many proteins is without influence on their functionality, they become unstable and are cleared faster from circulation. 

There are two major barriers in the mucosal absorption of peptide and protein—a penetration barrier and an enzymatic barrier (as supported by Lee ), which are relevant to nasal delivery. Taking those into consideration, basic factors influencing the nasal absorption of peptide and protein drugs will be discussed in this section. 

Both the protein and fat components in milk influence the properties of food, but the ability of the milk to impart desirable properties to food is mostly influenced by the physical functional properties of the milk protein components (Kinsella, 1984 Mulvihill and Fox, 1989). The inherent functionality of milk proteins is related to the structural/ conformational properties of protein, which is influenced by both the intrinsic properties of the protein and extrinsic factors. Modification of the protein composition or structure and the organization of the proteins within the dairy ingredient through the application of physical, chemical, or enzymatic processes, alone or in combination, enable the differentiation of the functionality of the ingredient and designing the required functionality for specific applications (Chobert, 2003 Foegeding et al., 2002). 

Protein-based ingredients contribute to the enhancement of food texture, flavor, and eye appeal [130], Functionality of protein ingredients can be enhanced also by enzymatic modifications. The factors influencing the choice of an appropriate enzyme for improvement of functional properties of proteins are as follows specificity of the enzyme, conformation of the protein, pH optimum, presence of activators and/or inhibitors, availability, thermostability, and financial causes. 

However, the activity of a heme(in) protein towards hydroperoxides is influenced by its steric accessibility to fatty acid hydroperoxides. Hydroperoxide binding to the Fe-porphyrin moiety of native catalase and peroxidase molecules is obviously not without interferences. The prosthetic group is free to promote hydroperoxide decomposition only after heat denaturation of the enzymes. Indeed, a model experiment with peroxidase showed that the peroxidation of linoleic acid increased by a factor of 10 when the enzyme was heated for 1 minute to 140 °C. As expected, the enzymatic activity of peroxidase decreased and was only 14%. Similar results were obtained in reaction systems containing catalase. 

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